The test suite spits this out during the export import test:

unable to propigate merge commit Ref "4475560d4e3958521ad12e2715aeee244ea0cf78" back to Ref "refs/heads/master"

It does not fail, but I think this is actually an indication of a bug.

The ref is a merge commit, because it's imported a tree from a special remote, and merged it. Which is a reasonable thing to want to do, even when on an adjusted branch. So, this needs to be dealt with somehow. --Joey